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-   -   FG layup schedule to achieve desired thickness (https://www.sailnet.com/forums/gear-maintenance/50467-fg-layup-schedule-achieve-desired-thickness.html)

dgr 01-13-2009 05:04 PM

FG layup schedule to achieve desired thickness
 
Here's the question: How do I translate thickness of a laminate to a layup schedule?

Sometime in the near future, I am going to have to do some core replacement on my decks. Once I cut into them, I will know how thick they should be and desire to replicate that thickness. Where the core is still 100%, the decks are fine so I believe that I should try to replicate the factory thickness.

Maybe I'm just approaching this from the wrong direction. But, I can't figure out how to measure the thickness short of doing a test layup. I could mess around with this and come up with something but, if there are formulas to get where I need to be, I'd like to work from that direction so I can get enough of what I need the first go around.

Thank you

NOLAsailing 01-13-2009 05:26 PM

If you want to be very precise, you can try to contact the builder and find out the laminate schedule.

However, that probably is not necessary. If you're a little over/under, it's not hard to sand it back down/build it up while fairing for paint prep. For most decks, 2 layers of 1708 biax topped with 1 layer of 10 oz cloth works well.

idontwantanaccount 01-14-2009 12:37 PM

Contact the fiberglass manufacturer. Some general, nonspecialty cloth info was posted at the link below.

Fiberglass thickness - Boat Design Forums

dgr 01-15-2009 04:40 PM

Thank you for the replies

I can't contact the builder as it is a Columbia. I really don't need to be that precise. I just want to have a general idea so that I can lay wet-on-wet when I do this. In the end, I want to avoid a springy deck or having to sand a whole layer off because I guessed wrong.

idontwanna,
Thank you for the link to the chart. That's a great starting point.

With all the experience on here, I'm surprised that those that have done this don't have an opinion. I'm thinking I should phrase this in such a way that what I'm trying to accomplish sounds like a really stupid idea. That seems like the best way to get a lot of responses :laugher :laugher

NOLAsailing 01-15-2009 04:53 PM

Quote:

I just want to have a general idea so that I can lay wet-on-wet when I do this
dgr - you're not going to want to build up all of the layers at once as the excessive heat can compromise the laminate. Depending on the weight of the glass, you'll be limited to 2 or three layers at a time.

dgr 01-15-2009 07:26 PM

Jason,
Thanks for that. So, what are the options to avoiding amine blush and insuring the highest bond strength between layers? Or can I go polyester or vinylester and just wax the last layup. It seems to me that everyone that does this type of work is using epoxy but I'm open to whatever will achieve the desired end result.

NOLAsailing 01-15-2009 08:25 PM

The amine blush is easy to address. Just spray the cured resin with water and srub it with a scotch brite pad - you don't need to scour it, just rub it down. Not a big deal (don't skip the step, but a decent scrub will remove any of the blush).

Forget poly or vinylester resins. They're OK for an initial build, but they have very poor secondary bonding characteristics. For a repair, epoxy is the only way to go.

sailingdog 01-15-2009 11:00 PM

Some epoxies don't blush or have a much reduced blush, like MAS epoxies...Or you can choose to lay up while the first layer is still tacky, before it cures fully.

The main reason most people go with Epoxy resins is because Epoxy resins have much better secondary (adhesive) bonding characteristics than do vinylester and polyester resins. Polyester and vinylester resins are much weaker when they can't form primary (chemical) bonds and have to rely on secondary (adhesive) bonding.

Two things to be aware of. First, epoxy resins deform and weaken at much lower temperatures than do vinylester and polyester resins, so you need to paint or gelcoat epoxy resin work in fairly light colors if the work is exterior. Second, epoxy resins are also subject to UV-degradation, so they need to be coated with something to protect them—paint or gelcoat.

Quote:

Originally Posted by dgr (Post 432647)
Jason,
Thanks for that. So, what are the options to avoiding amine blush and insuring the highest bond strength between layers? Or can I go polyester or vinylester and just wax the last layup. It seems to me that everyone that does this type of work is using epoxy but I'm open to whatever will achieve the desired end result.




dgr 01-16-2009 02:01 PM

SD,
Are you suggesting I do this from the inside? ;) Next thing, you'll be telling my I'm short two hulls :D :D

Seriously, thanks for the pointers. Laying up while the previous layup is green was what I was hoping to do. I will definitely be painting my deck white or some other non-dark color.

CrazyRu 01-16-2009 03:13 PM

If you use major brand names epoxy - West system, MAS etc, there is no amine blush when using slow hardeners.


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